Simplify the following expression: $r = \dfrac{3}{4y + 8} \div \dfrac{9}{10y}$
Dividing by an expression is the same as multiplying by its inverse. $r = \dfrac{3}{4y + 8} \times \dfrac{10y}{9}$ When multiplying fractions, we multiply the numerators and the denominators. $r = \dfrac{ 3 \times 10y } { (4y + 8) \times 9}$ $r = \dfrac{30y}{36y + 72}$ Simplify: $r = \dfrac{5y}{6y + 12}$